Abstract: An earth-boring bit has a bit body and at least one cutter rotatably secured to the bit body. The cutter has a cutter shell surface including a gage surface intersecting a heel surface. A plurality of hard metal inserts are arranged in generally circumferential rows on the cutter and include a heel row of heel inserts on the heel surface of the cutter and a gage row of gage inserts on the gage surface of the cutter. At least one scraper insert, formed of material more wear-resistant than that of the cutter shell surface, is secured to the cutter shell surface generally at the intersection of the gage and heel surfaces. The scraper insert includes a gage and a heel insert surface. The gage and heel surfaces of the scraper insert converge to define a cutting edge for engagement with the sidewall of the borehole, the heel insert surface defining a positive rake angle with respect to the sidewall of the borehole of between 0 and 15 degrees.

Abstract: An earth-boring bit has a bit body and at least one cutter rotatably secured to the bit body. The cutter has a cutter shell surface including a gage surface intersecting a heel surface. A plurality of hard metal inserts are arranged in generally circumferential rows on the cutter and include a heel row of heel inserts on the heel surface of the cutter and a gage row of gage inserts on the gage surface of the cutter. At least one scraper insert, formed of material more wear-resistant than that of the cutter shell surface, is secured to the cutter shell surface generally at the intersection of the gage and heel surfaces. The scraper insert includes a gage and a heel insert surface. The gage and heel surfaces of the scraper insert converge to define a cutting edge for engagement with the sidewall of the borehole, the insert surface defining a positive rake angle with respect to the sidewall of the borehole of between 0 and 15 degrees.

Abstract: An earth-boring bit is provided with three cutters, at least one of the three cutters are provided with a heel cutting structure defined by a plurality of heel inserts having crests thereon, the heel inserts being disposed in at least one substantially circumferential heel row and the crests of the heel inserts being generally aligned traversely to the rotational axis of the cutter. At least another of the cutters is provided with a substantially circumferential row of axial inserts having crests thereon disposed proximally to the base of the cutter, the crests of the axial inserts being generally aligned with the axis of rotation of the cutter.

Abstract: An earth-boring bit is provided with three cutters, two of the three cutters are provided with heel disk cutting elements defined by a pair of generally oppositely facing disk surfaces that generally continuously converge to define a circumferential heel disk crest. One of the two cutters having heel disk elements is further provided with an inner disk cutting element.

Abstract: A three cone earth boring bit having circumferential rows of earth disintegrating teeth of wear resistant inserts of selected projection from the cone surfaces, one cone having an inner row separated from a heel row by a narrow circumferential groove and second cone having a hell-catching row that intermeshes with the narrow groove by an amount to minimize balling. A nozzle directs a jet stream with a high velocity core past the cone and inserts of adjacent cutters to the bore hole bottom to break up the filter cake while the lower velocity skirt strikes the material packed between the inserts of adjacent cores. A row of small diameter, recessed reaming inserts replaces the conventional heel row on the cone having a hell-catching row, thus providing space for the lateral displacement of the material generated between adjacent inserts in the critical heel-catching row.